Competition between the β-hydroxylation of a primary and a tertiary carbon atom in rats

Article abstract of DOI:10.1016/S0223-5234(00)00110-0

In order to study the effect of steric hindrance on competition between two kinds of β-hydroxylation, a compound bearing on a pyrimidinetrione nucleus both a branched side chain with a tertiary carbon atom in position β (isobutyl group) and a linear side chain (ethyl group), was selected and administered to rats. Urine and faeces were collected and extracted. Hydroxymetabolites and their derivatives were isolated and then identified. The β-hydroxylation of the linear chain was more important than the β-hydroxylation of the branched chain. Steric hindrance plays a decisive role in this regioselectivity.